This invention generally relates to vehicle suspension systems and more particularly, to a system that increases roll rate responsive to the wheels of the vehicle being turned.
Modern day vehicle suspensions include a variety of components that are intended to make the vehicle ride as comfortable as possible while providing safe travel. Example components include shock absorbers at each of the wheels and stabilizer bars extending across a vehicle between wheels. The stabilizer bars effectively couple the vehicle ride and roll performance. Stabilizer bars are useful for preventing vehicle body roll during turns. Stabilizer bars, however, also add an unwanted spring rate to the suspension when one vehicle wheel encounters a road surface that is different than that encountered by the other wheel. For example, if one wheel hits a bump while the other does not, the spring rate on the wheel that hits the bump increases because of the stabilizer bar. The increased spring rate reduces ride comfort. While stabilizer bars are useful, it is desirable to modify their performance to address the competing needs for stability and ride comfort.
Adjusting the roll rate has been done in the racing industry. In those arrangements, a driver manually adjusts the roll rate to accommodate different fuel levels or other factors affecting the race car handling. There has not been an automatically adjustable arrangement nor one that changes the roll rate to accommodate the competing needs for stability and comfort.
Accordingly, there is a need for an arrangement where the performance of the stabilizer bar is enhanced under conditions where the roll rate must be at a certain level while the stabilizer bar performance can be effectively reduced when the roll rate can be relatively lower. This invention provides such an arrangement in a way that effectively couples the roll rate to the steering angle of the vehicle wheels, which has not been done before.
In general terms, this invention is an assembly for use in a vehicle suspension system that automatically adjusts the roll rate. A first element of the assembly rotates about a steering axis as an associated wheel on the vehicle is turned. A stabilizer bar is supported on the vehicle to counteract forces on the vehicle that otherwise tend to cause the vehicle to roll during a turn. A stiffness element is coupled with the stabilizer bar and automatically adjusts a stiffness of the assembly responsive to the first element rotating.
In one example the stiffness element is a metallic plate that is mechanically linked with a knuckle associated with the vehicle suspension at a corresponding wheel. The mechanical linkage provides that whenever the knuckle rotates about a steering axis, the plate rotates from a first orientation into a second orientation so that the roll rate is increased as the steering angle of the wheel assembly increases.
The various features and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the currently preferred arrangement. The drawings that accompany the detailed description can be briefly described as follows.